This invention relates to the preparation of catalyst compositions comprising a high surface area, zinc-modified, crystalline silica molecular sieve, essentially free of aluminum, incorporated into an inorganic matrix and to processes for propylating toluene accomplished by contacting toluene and a propylating agent under hydrocarbon conversion conditions with said compositions. More particularly, the invention relates to the preparation without the use of alkali metal ion or ammonia of high surface area, essentially free of aluminum, crystalline silica molecular sieves which have been modified by incorporation of a small amount of zinc, and toluene conversion processes, using catalyst compositions made from the sieves by incorporating such sieves in an inorganic matrix, involving the reaction of propylene and toluene to form a product in which the isopropyltoluene-to-n-propyltoluene isomer ratio is high and the ortho- and metacymene content of the isopropyltoluene fraction is very small compared to the paracymene content. This novel process offers a simple route from toluene to a paracymene product having greatly reduced isomer purification problems.
U.S. Pat. No. 4,254,296 describes a process for the preparation of tertiary olefins employing a crystalline silica having a high specific surface area, modified or unmodified with an oxide of certain metals including zinc capable of entering the silica lattice as a substitute for silicon or as a salt of polysilicic acids. Only the modifying elements chromium, aluminum and beryllium are shown in the Examples. In U.K. Patent Application No. 2,024,790A, high specific surface area crystalline silicas are taught, wherein certain elements, e.g. zinc, are said to have entered the crystal lattice of the silica in place of silicon atoms or in the form of salts of bisilicic or polysilicic acids. A zinc Example is given. These acidic, thermally stable materials are suggested as catalysts for a large number of reactions including the methylation of toluene to xylenes, particularly paraxylene. U.S. Pat. Nos. 4,423,269, 4,423,268 and 4,417,087 describe processes for oligomerization of gaseous olefins over intermediate pore size crystalline silicas including silicalite, chromia silicates (CZM) and U.S. Pat. No. Re. 29,948 organosilicates as described in U.S. Pat. No. Re. 29,948, or silicas containing significant amounts of alumina. Zinc can be incorporated into these materials for activity and stability using standard impregnation and ion exchange techniques. U.S. Pat. No. 4,329,328 teaches the synthesis of small pore "A type" zincosilicate or noncrystalline sodium zincosilicates. U.S. Pat. No. 4,291,182 teaches a process for the preparation of aromatic hydrocarbons and hydrogen from butane over crystalline silicates promoted by zinc incorporated by impregnation or ion exchange. In U.S. Pat. No. 3,894,104, use of a crystalline aluminosilicate zeolite modified by incorporation (exchanged, impregnated and/or vapor deposited) with one of a number of metals including zinc to catalyze aromatization of a heteroatom-substituted hydrocarbon is taught. In U.S. Pat. No. 1,728,732, materials made from a soluble silicate, an alkali metal compound and a heavy metal salt (including zinc salts) which, depending on the proportions used, resemble aluminosilicates were synthesized, and some are said to be useful as catalysts.